U.S. patent application number 11/281365 was filed with the patent office on 2006-05-25 for probe card having deeply recessed trench and method for manufacturing the same.
This patent application is currently assigned to UniTest Incorporation. Invention is credited to Kukjin Chun, Doo Yun Chung, Chi Hwan Jeong, Bong Hwan Kim.
Application Number | 20060109017 11/281365 |
Document ID | / |
Family ID | 36460369 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060109017 |
Kind Code |
A1 |
Kim; Bong Hwan ; et
al. |
May 25, 2006 |
Probe card having deeply recessed trench and method for
manufacturing the same
Abstract
The present invention relates to a probe card that a probe of
the probe card is movable only in a vertical direction using a
trench to improve a electrical or a mechanical characteristic and
to automatically limit the vertical movement thereof within a
predetermined range. A pitch may be reduced so as to correspond to
a decreasing distance between pads. A flatness of a probe tip may
be maintained within a few micrometers using a semiconductor
manufacturing process. 32 simultaneous parallel testing is possible
contrary to a convention probe card. A wafer level testing is
possible, and time and cost for a wafer testing are reduced.
Inventors: |
Kim; Bong Hwan; (Seoul,
KR) ; Chun; Kukjin; (Seoul, KR) ; Chung; Doo
Yun; (Seoul, KR) ; Jeong; Chi Hwan; (Seoul,
KR) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
UniTest Incorporation
|
Family ID: |
36460369 |
Appl. No.: |
11/281365 |
Filed: |
November 18, 2005 |
Current U.S.
Class: |
324/754.07 |
Current CPC
Class: |
G01R 3/00 20130101; G01R
1/07342 20130101 |
Class at
Publication: |
324/754 |
International
Class: |
G01R 31/02 20060101
G01R031/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 24, 2004 |
KR |
10-2004-0096875 |
Claims
1. A probe card comprising: a plurality of probes of a cantilever
type consisting of a probe tip and a probe beam; and a single
crystalline silicon substrate having a plurality of through-hole
contact members disposed therein, each of the plurality of the
through-hole contact members having a conductive material therein
for electrically connecting each of the plurality of the probes to
a test circuit, a plurality of trenches disposed in the substrate,
the plurality of trenches having the plurality of the probes
attached thereto so as to guide a movement of the plurality of the
probes in a vertical direction, and an insulating film for
insulating a portion of the conductive material other than a
portion where the plurality of the probes is in a direct contact
with the conductive material.
2. The probe card in accordance with claim 1, wherein a width or a
length of the probe tip is larger than a width of the trench so as
to limit the movement in the vertical direction.
3. The probe card in accordance with claim 1, wherein the probe is
disposed on a wafer which is separated after bonding the probe to
the single crystalline silicon substrate.
4. The probe card in accordance with claim 1, wherein the probe is
composed of a material selected from the group consisting of Cu and
an alloy containing Cu including Be--Cu.
5. The probe card in accordance with claim 1, wherein the probe is
composed of a material selected from the group consisting of Ni or
an alloy containing Ni including Ni--W, Ni--Co, Ni--Mn, Ni--Fe and
Ni--Cr.
6. The probe card in accordance with claim 1, wherein the
insulating film is an oxide film or a nitride film.
7. The probe card in accordance with claim 1, wherein the
through-hole contact member further comprising: a undoped
polysilicon layer disposed on the insulating film, wherein the
conductive material is disposed on the undoped polysilicon layer by
an electro-plating.
8. The probe card in accordance with claim 1, wherein the
through-hole contact member further comprising: a undoped
polysilicon layer disposed on the insulating film; an Au seed layer
disposed on the undoped polysilicon layer, wherein the conductive
material is disposed on the Au seed layer by an
electro-plating.
9. The probe card in accordance with claim 1, wherein the
through-hole contact member further comprising: a undoped
polysilicon layer disposed on the insulating film; wherein the
conductive material is disposed on the undoped polysilicon layer by
depositing a CVD tungsten film.
10. The probe card in accordance with claim 1, wherein the
through-hole contact member further comprising: a undoped
polysilicon layer disposed on the insulating film; and a CVD Cu
film deposited as a seed layer, wherein the conductive material is
disposed on the CVD Cu film.
11. The probe card in accordance with claim 1, wherein the
through-hole contact member further comprising: a undoped
polysilicon layer disposed on the insulating film; and a CVD
tungsten film deposited on the undoped polysilicon layer, wherein
Au is deposited on the CVD tungsten film as the conductive
material.
12. The probe card in accordance with claim 1, further comprising a
printed circuit board including the test circuit, wherein a test is
performed by applying an electrical signal from the printed circuit
board to the probe to transmit an electrical signal detected from
the probe to the printed circuit board through a connection between
a contacting portion of the printed circuit board and the
conductive material in the through-hole contact member.
13. A testing device for performing a wafer level test, the device
comprising a probe card in accordance with one of claims 1 through
12.
14. A method for manufacturing a probe card having a deeply
recessed trench, the method comprising steps of: forming a
through-hole in a single crystalline silicon substrate; forming an
insulating film in the single crystalline silicon substrate having
the through-hole; filling a conductive material in the through-hole
where the insulating film is formed, thereby forming a through-hole
contact member; forming a trench by an etching; forming a portion
where a probe is to be attached by an etching; forming an
insulating film exposing a portion where the probe and the
through-hole contact member are to be in contact; bonding a wafer
including the probe and the single crystalline silicon substrate so
that the probe is in the trench; and separating the single
crystalline silicon substrate including the probe from the
wafer.
15. The method in accordance with claim 14, wherein the probe
comprises a probe tip having a width or a length larger than a
width of the trench so as to limit the movement in the vertical
direction.
16. The method in accordance with claim 14, wherein the probe is
formed by an electro-plating, a CVD or a sputtering using Cu or an
alloy containing Cu including Be--Cu.
17. The method in accordance with claim 14, wherein the probe is
formed by an electro-plating, a CVD or a sputtering using Ni or an
alloy containing Ni including Ni--W, Ni--Co, Ni--Mn, Ni--Fe and
Ni--Cr.
18. The method in accordance with claim 14, wherein the step of
filling the conductive material comprises: forming an undoped
polysilicon; and filling the through-hole with the conductive
material by electroless plating.
19. The method in accordance with claim 14, wherein the step of
filling the conductive material comprises: forming an undoped
polysilicon; and filling the through-hole with the conductive
material by electroless plating.
20. The method in accordance with claim 14, wherein the step of
filling the conductive material comprises: forming an undoped
polysilicon; depositing a CVD tungsten film; and electroplating the
conductive material.
21. The method in accordance with claim 14, wherein the step of
filling the conductive material comprises: forming an undoped
polysilicon; and depositing a CVD Cu film as a seed layer.
22. The method in accordance with claim 14, wherein the step of
filling the conductive material comprises: forming an undoped
polysilicon; and depositing a CVD tungsten film; and depositing
Au.
23. The method in accordance with claim 14, further comprising
attaching a printed circuit board including a test circuit so that
a contacting portion of the printed circuit board is connected to
the through-hole contact member.
Description
RELATED APPLICATIONS
[0001] The present disclosure relates to subject matter contained
in priority Korean Application No. 10-2004-0096875 filed on 24 Nov.
2004, which is herein expressly incorporated by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a probe card having a
deeply recessed trench and a method for manufacturing the same, and
more particularly to a probe card having a deeply recessed trench
and a method for manufacturing the same wherein the probe card is
manufactured using the single crystalline silicon substrate and an
oxide film or a nitride film is used as an insulating film to
facilitate a signal separation between the probes, wherein the
probe is movable only in a vertical direction using a trench to
improve a electrical or a mechanical characteristic and to
automatically limit the vertical movement thereof within a
predetermined range, and wherein a pitch may be reduced so as to
correspond to a decreasing distance between pads, a flatness of a
probe tip may be maintained within a few micrometers using a
semiconductor manufacturing process, 32 simultaneous parallel
testing is possible contrary to a convention probe card, a wafer
level testing is possible, and time and cost for a wafer testing
are reduced.
[0004] 2. Background of the Invention
[0005] Generally, during a manufacturing process of a semiconductor
integrated circuit such as a memory device, a non-memory device or
a logic device, a test for determining defectiveness of each of
chips is performed after manufacturing the chips on a wafer. The
test is carried out by connecting the probe card to a probe testing
device and applying a signal to the chip to be tested with probe
tips of the probe card being in contact with pads of the chip to be
tested.
[0006] Since a force of 1 gram force per tip is applied to between
the probe tips of the probe testing device and testing wafer
including the chip to be tested, the probe tip must withstand this
force, and must have a reliability to endure about one million
contacts with the wafer. Moreover, a contact resistance of the
probe tip should be less than 1 ohm, and a pitch should be less
than 45 .mu.m to correspond to a miniaturized semiconductor chip
design.
[0007] A detailed description of a conventional probe card is
disclosed in Korean Patent Application No. 10-2002-0076050 filed on
Dec. 2, 2002 by the applicant, titled "Cantilever-Type Probe Card
and Method for manufacturing the Same Using Silicon Micromachining
Technology".
[0008] As disclosed in Korean Patent Application No.
10-2002-0076050, the conventional probe card is disadvantageous in
an aspect of carrying out mass testing of wafer. For example, in
accordance with U.S. Pat. No. 6,087,840 which is referred to as a
conventional art in Korean Patent Application No. 10-2002-0076050,
a pitch of a pad cannot be reduced below 50 .mu.m because a
tungsten needle (probe needle) is manually mounted, and an entire
wafer cannot be tested in a single test so that relatively more
time and cost is required. Other conventional arts disclosed in
Korean Patent Application No. 10-2002-0076050 are also
disadvantageous in that the probe card is sensitive to external
shock or a temperature change, the pitch cannot be reduced below 50
.mu.m, and a parallel test is difficult. Moreover, a wafer level
test wherein the entire wafer is tested at once cannot be carried
out, and each chip should be tested separately, resulting in a long
testing time and a high testing cost.
[0009] In order to solve such problem, Korean Patent Application
No. 10-2002-0076050 discloses a cantilever type probe card and a
method for manufacturing the same wherein a through-hole is formed
at an edge portion of a silicon substrate such as SOI (Silicon On
Insulator) substrate, the through-hole is filled up with a
conductive layer, a spring and a tip are then formed at a center
portion of the SOI substrate by a photo lithography and etching
process, a metal line electrically connected to the conductive
layer in the through-hole is formed, and the conductive layer in
the through-hole is then bonded to, a metal line of a printed
circuit board.
[0010] FIG. 1 is a cross-sectional view illustrating a
configuration of a conventional probe card.
[0011] As shown, the cantilever type probe card in accordance with
Korean Patent Application No. 10-2002-0076050 comprises a printed
circuit board 110 and SOI substrate 120. A through-hole 125 is
formed in the SOI substrate 120 to be connected to the printed
circuit board 110, an end portion 130 of a tip and a spring 135 are
formed, a conductive material 138 is formed so that an electrical
signal may be applied from printed circuit board 110 to a pad 165
of a wafer the substrate 160 to be tested. The end portion 130 of
the tip and the spring 135 are hereinafter referred to as a probe
tip and a probe beam, respectively.
[0012] However, while a configuration of the cantilever type probe
card in accordance with Korean Patent Application No.
10-2002-0076050 is advantageous in that a pitch between tips may be
reduced and more than 32 parallel tests and a wafer level test are
possible, a contact between the probe beams or a damage of the
probe beam may occur due to a horizontal movement of the probe
beams when a force is applied diagonally instead of vertically.
Actually, when a pressure is applied to the probe beam, a
possibility of the damage and malfunction of the probe tip is
increased during an actual test because a lateral force as well as
a completely vertical force exists.
[0013] In order to solve above-described problem, Korean Patent
Application No. 10-2003-0022937, filed by Yulim Hitech Inc. on Apr.
11, 2003 and published on Oct. 10, 2004 titled "Needle Assembly of
Probe Card" disclose a configuration wherein a horizontal movement
of a probe tip due to a lateral force component is prevented by
forming a needle moving hole.
[0014] FIG. 2 is a cross-sectional view illustrating a
configuration of the probe card disclosed by Korean Patent
Application No. 10-2003-0022937. As shown, in accordance with the
probe card disclosed in Korean Patent Application No.
10-2003-0022937, a needle plate 220 is allowed to only move
vertically through a movable gap 215 and a moving hole 210 even
when the lateral force component with respect to the needle plate
220 exists to reduce the possibility of the damage and malfunction
of the probe tip.
[0015] Particularly, in accordance with the configuration of the
probe card disclosed by Korean Patent Application No.
10-2003-0022937, the needle plate 220 moves inside the moving hole
210, that is, in the vertical direction to solve an instability
that may occur when a width of the probe beam is smaller than a
thickness thereof as a distance between pads is reduced. Therefore,
a probe having a stable configuration for corresponding to the
reduced pitch is provided.
[0016] However, while the configuration of the probe card disclosed
by Korean Patent Application No. 10-2003-0022937 reduces the
possibility of the damage and malfunction of the probe, and the
pitch, a metal line process cannot be carried out directly on the
silicon substrate so that the metal line process should be carried
out through the interface board 240 and a metal line for testing is
formed between the interface board 240 and the printed circuit
board (not shown) because of the moving hole 210 in the silicon
substrate. Therefore, a configuration of the testing device is very
complex.
SUMMARY OF THE INVENTION
[0017] It is an object of the present invention to provide a probe
card having a deeply recessed trench and a method for manufacturing
the same wherein the probe card is manufactured using the single
crystalline silicon substrate and an oxide film or a nitride film
is used as an insulating film to facilitate a signal separation
between the probes, wherein the probe is movable only in a vertical
direction using a trench to improve a electrical or a mechanical
characteristic and to automatically limit the vertical movement
thereof within a predetermined range, and wherein a pitch may be
reduced so as to correspond to a decreasing distance between pads,
a flatness of a probe tip may be maintained within a few
micrometers using a semiconductor manufacturing process, 32
simultaneous parallel testing is possible contrary to a convention
probe card, a wafer level testing is possible, and time and cost
for a wafer testing are reduced.
[0018] In order to achieve the above-described objects of the
present invention, there is provided a probe card comprising: a
plurality of probes of a cantilever type consisting of a probe tip
and a probe beam; and a single crystalline silicon substrate having
a plurality of through-hole contact members disposed therein, each
of the plurality of the through-hole contact members having a
conductive material therein for electrically connecting each of the
plurality of the probes to a test circuit, a plurality of trenches
disposed in the substrate, the plurality of trenches having the
plurality of the probes attached thereto so as to guide a movement
of the plurality of the probes in a vertical direction, and an
insulating film for insulating a portion of the conductive material
other than a portion where the plurality of the probes is in a
direct contact with the conductive material.
[0019] In order to achieve the above-described objects of the
present invention, there is also provided a testing device for
performing a wafer level test, the device comprising the probe card
of the present invention.
[0020] In order to achieve the above-described objects of the
present invention, there is also provided a method for
manufacturing a probe card having a deeply recessed trench, the
method comprising steps of: forming a through-hole in a single
crystalline silicon substrate; forming an insulating film in the
single crystalline silicon substrate having the through-hole;
filling a conductive material in the through-hole where the
insulating film is formed, thereby forming a through-hole contact
member; forming a trench by an etching; forming a portion where a
probe is to be attached by an etching; forming an insulating film
exposing a portion where the probe and the through-hole contact
member are to be in contact; bonding a wafer including the probe
and the single crystalline silicon substrate so that the probe is
in the trench; and separating the single crystalline silicon
substrate including the probe from the wafer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a cross-sectional view illustrating a
configuration of a conventional probe card.
[0022] FIG. 2 is a cross-sectional view illustrating a
configuration of a conventional probe card.
[0023] FIG. 3 is a cross-sectional view illustrating a probe card
having a deeply recessed trench in accordance with the present
invention.
[0024] FIG. 4 is a bottom view illustrating a probe card having a
deeply recessed trench in accordance with the present
invention.
[0025] FIGS. 5a through 5e are cross-sectional views illustrating a
method for manufacturing a probe card having a deeply recessed
trench in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] A probe card having a deeply recessed trench and a method
for manufacturing the same in accordance with the present invention
will now be described in detail with reference to the accompanied
drawings.
[0027] FIG. 3 is a cross-sectional view illustrating a probe card
having a deeply recessed trench in accordance with the present
invention. Although the probe card having the deeply recessed
trench in accordance with the present invention comprises a
plurality of probes of a cantilever type consisting of a probe tip
350 and a probe beam 340, and a structure formed in a single
crystalline silicon substrate 310, only a single probe is shown in
FIG. 3 for a convenience of description.
[0028] Referring to FIG. 3, a trench 360 for guiding a movement of
the probe in a vertical direction is formed in the single
crystalline silicon substrate 310, and a through-hole penetrating
the single crystalline silicon substrate 310 is formed and by
filling the through-hole with a conductive material, a through-hole
contact member 330 is formed. The through-hole contact member
establishes an electrical connection to the probe.
[0029] In addition, a portion which is in a direct contact with the
probe is covered with the insulating film 320 except a contacting
portion 335 which is in contact with the through-hole contact
member 330 so as to prevent a mis-transmission of a signal by a
contact with the probe.
[0030] Moreover, the insulating film 320 is also formed in the
trench 360 to prevent a mis-transmission of a signal. The
insulating film 320 is, for example, an oxide film or a nitride
film.
[0031] Although not shown, the probe card of the present invention
may further comprise a printed circuit board including the test
circuit, and an electrical signal from the printed circuit board is
applied to the probe to transmit an electrical signal detected from
the probe to the printed circuit board by connecting the contacting
portion of the printed circuit board to the through-hole contact
member 330 in the through-hole.
[0032] The probe is preferably composed of a material selected from
the group consisting of Cu and an alloy containing Cu including
Be--Cu.
[0033] Alternatively, the probe is composed of a material selected
from the group consisting of Ni or an alloy containing Ni including
Ni--W, Ni--Co, Ni--Mn, Ni--Fe and Ni--Cr.
[0034] The probe is preferably, manufactured on a wafer (not shown)
which is separated after bonding the probe to the single
crystalline silicon substrate.
[0035] The through-hole contact member 330 comprises a conductive
material for electrically connecting the probe to a test
circuit.
[0036] In one embodiment of the invention, the through-hole contact
member 330 can further comprises a undoped polysilicon layer
disposed on the insulating film 320. The conductive material is
disposed on the undoped polysilicon layer by an electro-plating in
this embodiment.
[0037] In another embodiment of the invention, the through-hole
contact member 330 can further comprises a undoped polysilicon
layer disposed on the insulating film 320. The conductive material
is disposed on the undoped polysilicon layer by an electro-plating
in this embodiment.
[0038] In still another embodiment of the invention, the
through-hole contact member 330 can further comprises a undoped
polysilicon layer disposed on the insulating film 320. The
conductive material is disposed -on the undoped polysilicon layer
by depositing a CVD tungsten film in this embodiment.
[0039] In still another embodiment of the invention, the
through-hole contact member 330 can further comprises a undoped
polysilicon layer disposed on the insulating film 320 and a CVD Cu
film deposited as a seed layer. The conductive material is disposed
on the CVD Cu film in this embodiment.
[0040] In still another embodiment of the invention, the
through-hole contact member 330 can further comprises a undoped
polysilicon layer disposed on the insulating film and a CVD
tungsten film deposited on the undoped polysilicon layer. Au is
deposited on the CVD tungsten film as the conductive material in
this embodiment.
[0041] The probe card having the deeply recessed trench in
accordance with the present invention and the probe card disclosed
in Korean Patent Application No. 10-2003-0022937 are similar in
that a vertical movement of the probe is guided using a trench or a
needle moving hole. However, while a metal line forming process
cannot be carried out directly on a substrate because of a use of
the needle moving hole in the conventional art, the metal line
forming process can be carried out directly on the substrate
because the trench is used in the present invention. Therefore, an
interface board for a metal line is not required in accordance with
the present invention contrary to the conventional art.
[0042] A manufacturing of the probe, a formation of the
through-hole contact member 330 and a formation of an insulating
film 320 will be described along with a description of a method for
manufacturing a probe card having a deeply recessed trench.
[0043] In addition, "L" in drawings denotes a distance between the
probe tip 350 and the single crystalline silicon substrate 310, and
the vertical movement of the probe is limited to the distance
L.
[0044] FIG. 4 is a bottom view illustrating a probe card having a
deeply recessed trench in accordance with the present invention. As
shown, a plurality of probes consisting of probe tips 350a through
350n and probe beams 340a through 340n, a plurality of contacting
portion 335a through 335n for connecting the through-hole contact
member 330 of the single crystalline silicon substrate and the
plurality of the probes, insulating films 320a through 320n for
insulating each of the plurality of the probes and the single
crystalline silicon substrate, and a plurality of trenches 360a
through 360n for guiding a vertical movement of each of the
plurality of the probes are formed on a backside of the single
crystalline silicon substrate.
[0045] In addition, a length or a width of each of the probe tips
350a through 350n is larger than a width of the trench so that each
of the probe tips 350a through 350n may move vertically within the
distance denoted as "L" in FIG. 3. The probe tip has a pyramid
shape or a polygonal cone.
[0046] FIGS. 5a through 5e are cross-sectional views illustrating a
method for manufacturing a probe card having a deeply recessed
trench in accordance with the present invention.
[0047] Referring to FIG. 5a, the through-hole 330' is formed by
etching the single crystalline silicon substrate 310 which is
commonly used for semiconductor devices.
[0048] Thereafter, the insulating film 320 is formed on an inner
surface of the through-hole 330'.
[0049] Referring to FIG. 5b, the conductive material is filled in
the through-hole 330', thereby the through-hole contact member 330
is formed.
[0050] The filling the through-hole 330' may be carried out by
various methods. For example, an undoped polysilicon is formed via
a deposition, and then an Au layer is formed as a seed layer, and
finally the conductive material is filled in the through-hole by an
electro-plating or an electroless plating.
[0051] Alternatively, an undoped polysilicon is deposited, and the
conductive material is electroplated by depositing a CVD tungsten
film. In one embodiment, an undoped polysilicon layer is formed,
and then the conductive material is formed using a CVD film as a
seed layer, or an undoped polysilicon layer is formed, and then the
conductive material is formed using a CVD film, and finally Au is
deposited to be filled up by the conductive material.
[0052] Referring to FIG. 5c, a trench is formed by etching a bottom
surface of the insulating film 320 and forming a space for
attaching a cantilever type probe.
[0053] For example, the trench 360 of the single crystalline
silicon substrate 310 as well as the space 365 for attaching the
probe may be etched via a dry etching. Thereafter, an insulating
film 325 is formed such that a surface of the single crystalline
silicon substrate is insulated except a contacting portion 335
where the through-hole contact member 330 and the probe contact
each other.
[0054] Referring to FIG. 5d, a cantilever type probe is
manufactured on a wafer. An etching of a wafer is persormed to form
a probe tip and a probe beam.
[0055] As shown, a space for forming the probe tip 350 and the
probe beam 340 is formed in the wafer 410 by etching, an oxide film
420 is formed therein, and the probe tip 350 and the probe beam 340
are then formed.
[0056] The probe tip 350 and the probe beam 340 may be formed by an
electro-plating, a CVD or a sputtering using Cu or an alloy
containing Cu such as Be--Cu.
[0057] Alternately, the probe tip 350 and the probe beam 340 may be
formed by an electro-plating, a CVD or a sputtering using Ni or an
alloy containing Ni such as Ni--W, Ni--Co, Ni--Mn, Ni--Fe or
Ni--Cr.
[0058] The oxide film 420 facilitates a separation of the probe,
and removed by an etching process when the probe is separated after
being attached.
[0059] Referring to FIG. 5e, after the single crystalline silicon
substrate 310 of FIG. 5c and the wafer 410 including the probe
manufactured through the process of FIG. 5d are bonded, the wafer
410 is separated from the single crystalline silicon substrate 310
The single crystalline silicon substrate 310 having the trench
therein and the wafer 410 having the probe thereon may be bonded
via an electro-plating process using a material such as PbSn, AuSn,
and BiSn.
[0060] When the wafer 410 is separated after the bonding, the probe
consisting of the probe tip 350 and the probe beam 340 are attached
to the single crystalline silicon substrate 310.
[0061] Thereafter, the complete probe card is connected to a
printed circuit board using a lead, and protected by a resin such
as an epoxy.
[0062] While the present invention has been particularly shown and
described with reference to the preferred embodiment thereof, it
will be understood by those skilled in the art that various changes
in form and details may be effected therein without departing from
the spirit and scope of the invention as defined by the appended
claims.
* * * * *